The Briton who languished in a Cuban jail after being accused of spyingStephen Purvis has returned to Britain after spending 16 months in a Cuban jail on false spying and fraud charges. He speaks to Colin Freeman about the ordeal.

When the £400 million Bellomonte Golf and Country Club eventually opens for business, its pristine fairways will mark an elegantly landscaped route into the 21st century for Cuba. In a country that once banned golf as a "bourgeois sport", its five-star hotel, spa and luxury villa complex is the clearest sign that the communist outpost is finally embracing capitalism.

One man who is unlikely to attend any future opening ceremony, though, is Stephen Purvis, the Wimbledon-born architect whose firm, Coral Capital, was behind the Bellomonte development. Resident with his family in Cuba for 10 years, he was the ideal person to mastermind the flagship project of its tourist economy, having previously turned Havana's crumbling, colonial-era Saratoga Hotel into a chic hang-out favoured by the likes of Beyoncé and Naomi Campbell.

Last week, however, he was recovering back in London, after losing 16 months of his life – and 50lbs in weight – to a stint in the rather less comfortable accommodation of Cuba's prison system.

In an ordeal that could have been torn from the pages of a Graham Greene novel, Mr Purvis was falsely accused first of being a spy, and then of obscure breaches of finance laws, while never being told details of the allegations against him. He fled the island after a court released him a fortnight ago, following a trial conducted entirely in secret. Meanwhile, Coral's offices in Cuba have been shut down, and the country club project in which he has invested millions of pounds and five years of his life has been handed to a Chinese firm.

Yet he counts himself lucky. During his time in Havana's notorious Villa Marista spy interrogation centre, he feared he might never see the outside world again, or his wife Rachel and four children."It was grim, absolutely grim," he told The Sunday Telegraph. "Being accused of espionage is bad enough anywhere, let alone somewhere like Cuba. You get this overpowering sense of being forgotten by the world, and that you are about to receive a huge prison sentence for nothing at all."Mr Purvis, 52, spoke out last week to warn other British entrepreneurs of the risks in Cuba, which has courted foreign investors in recent years. They were risks he himself thought he no longer had to worry about, given that his own firm, financed by private European backers, was well established. Since setting up there in 2000, it has invested in everything from tourism through to factories and docks, and even financed El Benny, a film about the Cuban singer, Benny Moré.

Mr Purvis was also a pillar of Havana's expatriate community, working as vice-chairman of Havana's international school and producing a Cuban dance show that has toured London's West End.

Those connections, however, counted for nothing when in October 2011 Cuban police arrested Amado Fakhre, Coral's British-Lebanese chief executive, on charges of bribery and revealing state secrets. The move appears to have been part of a wider sweep against dozens of foreign businessmen, launched after Cuban intelligence became convinced that the occasional bribery which took place had become an epidemic.

Five months later, Mr Purvis was arrested. After five days of questioning at a "run-down villa in the middle of nowhere", he was put in "pre-emptive detention" in Villa Marista, which is where political prisoners are interrogated. Officials boast that, eventually, everyone "sings" after a stay there.

Mr Purvis says the jail was designed to send inmates mad. He was kept with three others in a filthy 8ft by 8ft cell, with the lights on around the clock and exercise limited to 15 minutes a week. Each prisoner was also assigned a personal interrogator who would even cut their toenails, fingernails and hair for them.

"They decide absolutely everything about your life. The idea is to separate you from your personal identity, so you lose a sense of who you are. Several inmates who passed through my cell went cuckoo, and there was an attempted suicide about once a month. You'd be trying to sleep at night and suddenly there'd be this terrible wail from some other cell."

His wife was admitted to hospital with stress and later flew back to Britain with their children for their own safety. Eight months later, the spying charge was switched to "economic crime", and he was moved to a special unit for foreigners at La Condesa prison. It was comfortable compared to Villa Marista, even though his new companions included murderers, Yardies and drug barons.

Mr Purvis passed the time by writing a script and drawing up business plans for inmates. An amateur artist, he also painted portraits of prisoners' wives and girlfriends.

It was not until three weeks before his trial last month that his Cuban lawyer finally got the charge sheet against him – an 8,000-page document that Mr Purvis was not allowed to see. He was convicted, though, only of the minor charge of conducting illegal currency transactions – something, he says, the central bank has authorised for years.

In the end, he received a two-and-a-half-year "non-custodial sentence" and was released on June 17, two days before Mr Fakhre. Since leaving Cuba he has been staying at the house of his mother Anne in London, reunited with Rachel and their children Joseph, 18, Max, 17, Poppy, 15 and Anna Rose 13.

Coral is now contemplating another tussle with the Cuban courts – this time a lawsuit to regain £10.6 million in confiscated company assets. But exactly why the Cuban authorities moved against the company remains a mystery.

One possibility is that the denunciation came from a business rival. Another, says Mr Purvis, is that the firm was simply the victim of an over-zealous anti-corruption trawl.

But he also believes a wider political game may be at work. Most of the arrested businessmen have been Westerners, while competitors from China and Venezuela have been left alone, suggesting a plan to clear Cuba's markets for countries Havana feels ideologically comfortable with.